#include <GL/glut.h>
void display(){
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_POLYGON);
    glVertex2f(-0.5,-0.5);
    glVertex2f(-0.5,0.5);
    glVertex2f(0.5,0.5);
    glVertex2f(0.5,-0.5);
    glEnd();
    glFlush();
}
int main(int argc,char *argv[]){
    glutInit(&argc,argv);
    glutCreateWindow("Simple");
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}
